Biased visual search in a homogenous background C Paeye, A Schütz, K R Gegenfurtner |
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Department of Psychology, Justus-Liebig-University Giessen, Germany
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| To account for eye movement strategies during visual search, Najemnik and Geisler [2005, Nature, 434, 387-391] elaborated a Bayesian model that updates its representation about the target location to plan the next fixation so as to maximize the information collected. Their model describes human performance well. We tested whether introducing a target location bias would affect the visual search strategies of naïve participants. An optimal observer would use such prior information to make the search more efficient. We presented a target four times more often in one quadrant of a 1/f background noise. We tested different target visibilities (d’ between four and one). The search efficiency was high (median fixation counts from three to ten, median detection times from two to five seconds). However, only three out of six participants modified their saccade sequences in favor of the quadrant containing the target more often. This is in contrast to recent studies observing statistical learning when subjects have to identify a target among several distinct items [eg. Jiang et al., 2013, J Exp Psychol, 39, 87-99]. Presumably it is more difficult to induce statistical learning when the target can appear at any position in a homogenous background. |
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